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authorNeil Schemenauer <nascheme@enme.ucalgary.ca>2001-02-27 04:45:05 (GMT)
committerNeil Schemenauer <nascheme@enme.ucalgary.ca>2001-02-27 04:45:05 (GMT)
commita35c688055c72e9442f6a82c3ec0e09654077975 (patch)
tree081386e63e64467a01558567750b371baa527f8e /Objects/obmalloc.c
parent29906eef3a56c43a4cd68a8706c75844b2384e59 (diff)
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Add Vladimir Marangozov's object allocator. It is disabled by default. This
closes SF patch #401229.
Diffstat (limited to 'Objects/obmalloc.c')
-rw-r--r--Objects/obmalloc.c743
1 files changed, 743 insertions, 0 deletions
diff --git a/Objects/obmalloc.c b/Objects/obmalloc.c
new file mode 100644
index 0000000..4fcd187
--- /dev/null
+++ b/Objects/obmalloc.c
@@ -0,0 +1,743 @@
+/* An object allocator for Python.
+
+ Here is an introduction to the layers of the Python memory architecture,
+ showing where the object allocator is actually used (layer +2), It is
+ called for every object allocation and deallocation (PyObject_New/Del),
+ unless the object-specific allocators implement a proprietary allocation
+ scheme (ex.: ints use a simple free list). This is also the place where
+ the cyclic garbage collector operates selectively on container objects.
+
+
+ Object-specific allocators
+ _____ ______ ______ ________
+ [ int ] [ dict ] [ list ] ... [ string ] Python core |
++3 | <----- Object-specific memory -----> | <-- Non-object memory --> |
+ _______________________________ | |
+ [ Python's object allocator ] | |
++2 | ####### Object memory ####### | <------ Internal buffers ------> |
+ ______________________________________________________________ |
+ [ Python's raw memory allocator (PyMem_ API) ] |
++1 | <----- Python memory (under PyMem manager's control) ------> | |
+ __________________________________________________________________
+ [ Underlying general-purpose allocator (ex: C library malloc) ]
+ 0 | <------ Virtual memory allocated for the python process -------> |
+
+ =========================================================================
+ _______________________________________________________________________
+ [ OS-specific Virtual Memory Manager (VMM) ]
+-1 | <--- Kernel dynamic storage allocation & management (page-based) ---> |
+ __________________________________ __________________________________
+ [ ] [ ]
+-2 | <-- Physical memory: ROM/RAM --> | | <-- Secondary storage (swap) --> |
+
+*/
+/*==========================================================================*/
+
+/* A fast, special-purpose memory allocator for small blocks, to be used
+ on top of a general-purpose malloc -- heavily based on previous art. */
+
+/* Vladimir Marangozov -- August 2000 */
+
+/*
+ * "Memory management is where the rubber meets the road -- if we do the wrong
+ * thing at any level, the results will not be good. And if we don't make the
+ * levels work well together, we are in serious trouble." (1)
+ *
+ * (1) Paul R. Wilson, Mark S. Johnstone, Michael Neely, and David Boles,
+ * "Dynamic Storage Allocation: A Survey and Critical Review",
+ * in Proc. 1995 Int'l. Workshop on Memory Management, September 1995.
+ */
+
+/* #undef WITH_MEMORY_LIMITS */ /* disable mem limit checks */
+#define WITH_MALLOC_HOOKS /* for profiling & debugging */
+
+/*==========================================================================*/
+
+/*
+ * Public functions exported by this allocator.
+ *
+ * -- Define and use these names in your code to obtain or release memory --
+ */
+#define _THIS_MALLOC PyCore_OBJECT_MALLOC_FUNC
+#define _THIS_CALLOC /* unused */
+#define _THIS_REALLOC PyCore_OBJECT_REALLOC_FUNC
+#define _THIS_FREE PyCore_OBJECT_FREE_FUNC
+
+/*
+ * Underlying allocator's functions called by this allocator.
+ * The underlying allocator is usually the one which comes with libc.
+ *
+ * -- Don't use these functions in your code (to avoid mixing allocators) --
+ *
+ * Redefine these __only__ if you are using a 3rd party general purpose
+ * allocator which exports functions with names _other_ than the standard
+ * malloc, calloc, realloc, free.
+ */
+#define _SYSTEM_MALLOC PyCore_MALLOC_FUNC
+#define _SYSTEM_CALLOC /* unused */
+#define _SYSTEM_REALLOC PyCore_REALLOC_FUNC
+#define _SYSTEM_FREE PyCore_FREE_FUNC
+
+/*
+ * If malloc hooks are needed, names of the hooks' set & fetch
+ * functions exported by this allocator.
+ */
+#ifdef WITH_MALLOC_HOOKS
+#define _SET_HOOKS _PyCore_ObjectMalloc_SetHooks
+#define _FETCH_HOOKS _PyCore_ObjectMalloc_FetchHooks
+#endif
+
+/*==========================================================================*/
+
+/*
+ * Allocation strategy abstract:
+ *
+ * For small requests, the allocator sub-allocates <Big> blocks of memory.
+ * Requests greater than 256 bytes are routed to the system's allocator.
+ *
+ * Small requests are grouped in size classes spaced 8 bytes apart, due
+ * to the required valid alignment of the returned address. Requests of
+ * a particular size are serviced from memory pools of 4K (one VMM page).
+ * Pools are fragmented on demand and contain free lists of blocks of one
+ * particular size class. In other words, there is a fixed-size allocator
+ * for each size class. Free pools are shared by the different allocators
+ * thus minimizing the space reserved for a particular size class.
+ *
+ * This allocation strategy is a variant of what is known as "simple
+ * segregated storage based on array of free lists". The main drawback of
+ * simple segregated storage is that we might end up with lot of reserved
+ * memory for the different free lists, which degenerate in time. To avoid
+ * this, we partition each free list in pools and we share dynamically the
+ * reserved space between all free lists. This technique is quite efficient
+ * for memory intensive programs which allocate mainly small-sized blocks.
+ *
+ * For small requests we have the following table:
+ *
+ * Request in bytes Size of allocated block Size class idx
+ * ----------------------------------------------------------------
+ * 1-8 8 0
+ * 9-16 16 1
+ * 17-24 24 2
+ * 25-32 32 3
+ * 33-40 40 4
+ * 41-48 48 5
+ * 49-56 56 6
+ * 57-64 64 7
+ * 65-72 72 8
+ * ... ... ...
+ * 241-248 248 30
+ * 249-256 256 31
+ *
+ * 0, 257 and up: routed to the underlying allocator.
+ */
+
+/*==========================================================================*/
+
+/*
+ * -- Main tunable settings section --
+ */
+
+/*
+ * Alignment of addresses returned to the user. 8-bytes alignment works
+ * on most current architectures (with 32-bit or 64-bit address busses).
+ * The alignment value is also used for grouping small requests in size
+ * classes spaced ALIGNMENT bytes apart.
+ *
+ * You shouldn't change this unless you know what you are doing.
+ */
+
+#define ALIGNMENT 8 /* must be 2^N */
+#define ALIGNMENT_SHIFT 3
+#define ALIGNMENT_MASK (ALIGNMENT - 1)
+
+/*
+ * Max size threshold below which malloc requests are considered to be
+ * small enough in order to use preallocated memory pools. You can tune
+ * this value according to your application behaviour and memory needs.
+ *
+ * The following invariants must hold:
+ * 1) ALIGNMENT <= SMALL_REQUEST_THRESHOLD <= 256
+ * 2) SMALL_REQUEST_THRESHOLD == N * ALIGNMENT
+ *
+ * Although not required, for better performance and space efficiency,
+ * it is recommended that SMALL_REQUEST_THRESHOLD is set to a power of 2.
+ */
+
+/*
+ * For Python compiled on systems with 32 bit pointers and integers,
+ * a value of 64 (= 8 * 8) is a reasonable speed/space tradeoff for
+ * the object allocator. To adjust automatically this threshold for
+ * systems with 64 bit pointers, we make this setting depend on a
+ * Python-specific slot size unit = sizeof(long) + sizeof(void *),
+ * which is expected to be 8, 12 or 16 bytes.
+ */
+
+#define _PYOBJECT_THRESHOLD ((SIZEOF_LONG + SIZEOF_VOID_P) * ALIGNMENT)
+
+#define SMALL_REQUEST_THRESHOLD _PYOBJECT_THRESHOLD /* must be N * ALIGNMENT */
+
+#define NB_SMALL_SIZE_CLASSES (SMALL_REQUEST_THRESHOLD / ALIGNMENT)
+
+/*
+ * The system's VMM page size can be obtained on most unices with a
+ * getpagesize() call or deduced from various header files. To make
+ * things simpler, we assume that it is 4K, which is OK for most systems.
+ * It is probably better if this is the native page size, but it doesn't
+ * have to be.
+ */
+
+#define SYSTEM_PAGE_SIZE (4 * 1024)
+#define SYSTEM_PAGE_SIZE_MASK (SYSTEM_PAGE_SIZE - 1)
+
+/*
+ * Maximum amount of memory managed by the allocator for small requests.
+ */
+
+#ifdef WITH_MEMORY_LIMITS
+#ifndef SMALL_MEMORY_LIMIT
+#define SMALL_MEMORY_LIMIT (64 * 1024 * 1024) /* 64 MB -- more? */
+#endif
+#endif
+
+/*
+ * The allocator sub-allocates <Big> blocks of memory (called arenas) aligned
+ * on a page boundary. This is a reserved virtual address space for the
+ * current process (obtained through a malloc call). In no way this means
+ * that the memory arenas will be used entirely. A malloc(<Big>) is usually
+ * an address range reservation for <Big> bytes, unless all pages within this
+ * space are referenced subsequently. So malloc'ing big blocks and not using
+ * them does not mean "wasting memory". It's an addressable range wastage...
+ *
+ * Therefore, allocating arenas with malloc is not optimal, because there is
+ * some address space wastage, but this is the most portable way to request
+ * memory from the system accross various platforms.
+ */
+
+#define ARENA_SIZE (256 * 1024 - SYSTEM_PAGE_SIZE) /* 256k - 1p */
+
+#ifdef WITH_MEMORY_LIMITS
+#define MAX_ARENAS (SMALL_MEMORY_LIMIT / ARENA_SIZE)
+#endif
+
+/*
+ * Size of the pools used for small blocks. Should be a power of 2,
+ * between 1K and SYSTEM_PAGE_SIZE, that is: 1k, 2k, 4k, eventually 8k.
+ */
+
+#define POOL_SIZE SYSTEM_PAGE_SIZE /* must be 2^N */
+#define POOL_SIZE_MASK SYSTEM_PAGE_SIZE_MASK
+#define POOL_MAGIC 0x74D3A651 /* authentication id */
+
+#define ARENA_NB_POOLS (ARENA_SIZE / POOL_SIZE)
+#define ARENA_NB_PAGES (ARENA_SIZE / SYSTEM_PAGE_SIZE)
+
+/*
+ * -- End of tunable settings section --
+ */
+
+/*==========================================================================*/
+
+/*
+ * Locking
+ *
+ * To reduce lock contention, it would probably be better to refine the
+ * crude function locking with per size class locking. I'm not positive
+ * however, whether it's worth switching to such locking policy because
+ * of the performance penalty it might introduce.
+ *
+ * The following macros describe the simplest (should also be the fastest)
+ * lock object on a particular platform and the init/fini/lock/unlock
+ * operations on it. The locks defined here are not expected to be recursive
+ * because it is assumed that they will always be called in the order:
+ * INIT, [LOCK, UNLOCK]*, FINI.
+ */
+
+/*
+ * Python's threads are serialized, so object malloc locking is disabled.
+ */
+#define SIMPLELOCK_DECL(lock) /* simple lock declaration */
+#define SIMPLELOCK_INIT(lock) /* allocate (if needed) and initialize */
+#define SIMPLELOCK_FINI(lock) /* free/destroy an existing lock */
+#define SIMPLELOCK_LOCK(lock) /* acquire released lock */
+#define SIMPLELOCK_UNLOCK(lock) /* release acquired lock */
+
+/*
+ * Basic types
+ * I don't care if these are defined in <sys/types.h> or elsewhere. Axiom.
+ */
+
+#undef uchar
+#define uchar unsigned char /* assuming == 8 bits */
+
+#undef ushort
+#define ushort unsigned short /* assuming >= 16 bits */
+
+#undef uint
+#define uint unsigned int /* assuming >= 16 bits */
+
+#undef ulong
+#define ulong unsigned long /* assuming >= 32 bits */
+
+#undef off_t
+#define off_t uint /* 16 bits <= off_t <= 64 bits */
+
+/* When you say memory, my mind reasons in terms of (pointers to) blocks */
+typedef uchar block;
+
+/* Pool for small blocks */
+struct pool_header {
+ union { block *__padding;
+ uint count; } ref; /* number of allocated blocks */
+ block *freeblock; /* pool's free list head */
+ struct pool_header *nextpool; /* next pool of this size class */
+ struct pool_header *prevpool; /* previous pool "" */
+ struct pool_header *pooladdr; /* pool address (always aligned) */
+ uint magic; /* pool magic number */
+ uint szidx; /* block size class index */
+ uint capacity; /* pool capacity in # of blocks */
+};
+
+typedef struct pool_header *poolp;
+
+#undef ROUNDUP
+#define ROUNDUP(x) (((x) + ALIGNMENT_MASK) & ~ALIGNMENT_MASK)
+#define POOL_OVERHEAD ROUNDUP(sizeof(struct pool_header))
+
+#define DUMMY_SIZE_IDX 0xffff /* size class of newly cached pools */
+
+/*==========================================================================*/
+
+/*
+ * This malloc lock
+ */
+SIMPLELOCK_DECL(__malloc_lock);
+#define LOCK() SIMPLELOCK_LOCK(__malloc_lock)
+#define UNLOCK() SIMPLELOCK_UNLOCK(__malloc_lock)
+#define LOCK_INIT() SIMPLELOCK_INIT(__malloc_lock)
+#define LOCK_FINI() SIMPLELOCK_FINI(__malloc_lock)
+
+/*
+ * Pool table -- doubly linked lists of partially used pools
+ */
+#define PTA(x) ((poolp )((uchar *)&(usedpools[2*(x)]) - 2*sizeof(block *)))
+#define PT(x) PTA(x), PTA(x)
+
+static poolp usedpools[2 * ((NB_SMALL_SIZE_CLASSES + 7) / 8) * 8] = {
+ PT(0), PT(1), PT(2), PT(3), PT(4), PT(5), PT(6), PT(7)
+#if NB_SMALL_SIZE_CLASSES > 8
+ , PT(8), PT(9), PT(10), PT(11), PT(12), PT(13), PT(14), PT(15)
+#if NB_SMALL_SIZE_CLASSES > 16
+ , PT(16), PT(17), PT(18), PT(19), PT(20), PT(21), PT(22), PT(23)
+#if NB_SMALL_SIZE_CLASSES > 24
+ , PT(24), PT(25), PT(26), PT(27), PT(28), PT(29), PT(30), PT(31)
+#if NB_SMALL_SIZE_CLASSES > 32
+ , PT(32), PT(33), PT(34), PT(35), PT(36), PT(37), PT(38), PT(39)
+#if NB_SMALL_SIZE_CLASSES > 40
+ , PT(40), PT(41), PT(42), PT(43), PT(44), PT(45), PT(46), PT(47)
+#if NB_SMALL_SIZE_CLASSES > 48
+ , PT(48), PT(49), PT(50), PT(51), PT(52), PT(53), PT(54), PT(55)
+#if NB_SMALL_SIZE_CLASSES > 56
+ , PT(56), PT(57), PT(58), PT(59), PT(60), PT(61), PT(62), PT(63)
+#endif /* NB_SMALL_SIZE_CLASSES > 56 */
+#endif /* NB_SMALL_SIZE_CLASSES > 48 */
+#endif /* NB_SMALL_SIZE_CLASSES > 40 */
+#endif /* NB_SMALL_SIZE_CLASSES > 32 */
+#endif /* NB_SMALL_SIZE_CLASSES > 24 */
+#endif /* NB_SMALL_SIZE_CLASSES > 16 */
+#endif /* NB_SMALL_SIZE_CLASSES > 8 */
+};
+
+/*
+ * Free (cached) pools
+ */
+static poolp freepools = NULL; /* free list for cached pools */
+
+/*
+ * Arenas
+ */
+static uint arenacnt = 0; /* number of allocated arenas */
+static uint watermark = ARENA_NB_POOLS; /* number of pools allocated from
+ the current arena */
+static block *arenalist = NULL; /* list of allocated arenas */
+static block *arenabase = NULL; /* free space start address in
+ current arena */
+
+/*
+ * Hooks
+ */
+#ifdef WITH_MALLOC_HOOKS
+static void *(*malloc_hook)(size_t) = NULL;
+static void *(*calloc_hook)(size_t, size_t) = NULL;
+static void *(*realloc_hook)(void *, size_t) = NULL;
+static void (*free_hook)(void *) = NULL;
+#endif /* !WITH_MALLOC_HOOKS */
+
+/*==========================================================================*/
+
+/* malloc */
+
+/*
+ * The basic blocks are ordered by decreasing execution frequency,
+ * which minimizes the number of jumps in the most common cases,
+ * improves branching prediction and instruction scheduling (small
+ * block allocations typically result in a couple of instructions).
+ * Unless the optimizer reorders everything, being too smart...
+ */
+
+void *
+_THIS_MALLOC(size_t nbytes)
+{
+ block *bp;
+ poolp pool;
+ poolp next;
+ uint size;
+
+#ifdef WITH_MALLOC_HOOKS
+ if (malloc_hook != NULL)
+ return (*malloc_hook)(nbytes);
+#endif
+
+ /*
+ * This implicitly redirects malloc(0)
+ */
+ if ((nbytes - 1) < SMALL_REQUEST_THRESHOLD) {
+ LOCK();
+ /*
+ * Most frequent paths first
+ */
+ size = (uint )(nbytes - 1) >> ALIGNMENT_SHIFT;
+ pool = usedpools[size + size];
+ if (pool != pool->nextpool) {
+ /*
+ * There is a used pool for this size class.
+ * Pick up the head block of its free list.
+ */
+ ++pool->ref.count;
+ bp = pool->freeblock;
+ if ((pool->freeblock = *(block **)bp) != NULL) {
+ UNLOCK();
+ return (void *)bp;
+ }
+ /*
+ * Reached the end of the free list, try to extend it
+ */
+ if (pool->ref.count < pool->capacity) {
+ /*
+ * There is room for another block
+ */
+ size++;
+ size <<= ALIGNMENT_SHIFT; /* block size */
+ pool->freeblock = (block *)pool + \
+ POOL_OVERHEAD + \
+ pool->ref.count * size;
+ *(block **)(pool->freeblock) = NULL;
+ UNLOCK();
+ return (void *)bp;
+ }
+ /*
+ * Pool is full, unlink from used pools
+ */
+ next = pool->nextpool;
+ pool = pool->prevpool;
+ next->prevpool = pool;
+ pool->nextpool = next;
+ UNLOCK();
+ return (void *)bp;
+ }
+ /*
+ * Try to get a cached free pool
+ */
+ pool = freepools;
+ if (pool != NULL) {
+ /*
+ * Unlink from cached pools
+ */
+ freepools = pool->nextpool;
+ init_pool:
+ /*
+ * Frontlink to used pools
+ */
+ next = usedpools[size + size]; /* == prev */
+ pool->nextpool = next;
+ pool->prevpool = next;
+ next->nextpool = pool;
+ next->prevpool = pool;
+ pool->ref.count = 1;
+ if (pool->szidx == size) {
+ /*
+ * Luckily, this pool last contained blocks
+ * of the same size class, so its header
+ * and free list are already initialized.
+ */
+ bp = pool->freeblock;
+ pool->freeblock = *(block **)bp;
+ UNLOCK();
+ return (void *)bp;
+ }
+ /*
+ * Initialize the pool header and free list
+ * then return the first block.
+ */
+ pool->szidx = size;
+ size++;
+ size <<= ALIGNMENT_SHIFT; /* block size */
+ bp = (block *)pool + POOL_OVERHEAD;
+ pool->freeblock = bp + size;
+ *(block **)(pool->freeblock) = NULL;
+ pool->capacity = (POOL_SIZE - POOL_OVERHEAD) / size;
+ UNLOCK();
+ return (void *)bp;
+ }
+ /*
+ * Allocate new pool
+ */
+ if (watermark < ARENA_NB_POOLS) {
+ /* commit malloc(POOL_SIZE) from the current arena */
+ commit_pool:
+ watermark++;
+ pool = (poolp )arenabase;
+ arenabase += POOL_SIZE;
+ pool->pooladdr = pool;
+ pool->magic = (uint )POOL_MAGIC;
+ pool->szidx = DUMMY_SIZE_IDX;
+ goto init_pool;
+ }
+ /*
+ * Allocate new arena
+ */
+#ifdef WITH_MEMORY_LIMITS
+ if (!(arenacnt < MAX_ARENAS)) {
+ UNLOCK();
+ goto redirect;
+ }
+#endif
+ /*
+ * With malloc, we can't avoid loosing one page address space
+ * per arena due to the required alignment on page boundaries.
+ */
+ bp = (block *)_SYSTEM_MALLOC(ARENA_SIZE + SYSTEM_PAGE_SIZE);
+ if (bp == NULL) {
+ UNLOCK();
+ goto redirect;
+ }
+ /*
+ * Keep a reference in the list of allocated arenas. We might
+ * want to release (some of) them in the future. The first
+ * word is never used, no matter whether the returned address
+ * is page-aligned or not, so we safely store a pointer in it.
+ */
+ *(block **)bp = arenalist;
+ arenalist = bp;
+ arenacnt++;
+ watermark = 0;
+ /* Page-round up */
+ arenabase = bp + (SYSTEM_PAGE_SIZE -
+ ((off_t )bp & SYSTEM_PAGE_SIZE_MASK));
+ goto commit_pool;
+ }
+
+ /* The small block allocator ends here. */
+
+ redirect:
+
+ /*
+ * Redirect the original request to the underlying (libc) allocator.
+ * We jump here on bigger requests, on error in the code above (as a
+ * last chance to serve the request) or when the max memory limit
+ * has been reached.
+ */
+ return (void *)_SYSTEM_MALLOC(nbytes);
+}
+
+/* free */
+
+void
+_THIS_FREE(void *p)
+{
+ poolp pool;
+ poolp next, prev;
+ uint size;
+ off_t offset;
+
+#ifdef WITH_MALLOC_HOOKS
+ if (free_hook != NULL) {
+ (*free_hook)(p);
+ return;
+ }
+#endif
+
+ if (p == NULL) /* free(NULL) has no effect */
+ return;
+
+ offset = (off_t )p & POOL_SIZE_MASK;
+ pool = (poolp )((block *)p - offset);
+ if (pool->pooladdr != pool || pool->magic != (uint )POOL_MAGIC) {
+ _SYSTEM_FREE(p);
+ return;
+ }
+
+ LOCK();
+ /*
+ * At this point, the pool is not empty
+ */
+ if ((*(block **)p = pool->freeblock) == NULL) {
+ /*
+ * Pool was full
+ */
+ pool->freeblock = (block *)p;
+ --pool->ref.count;
+ /*
+ * Frontlink to used pools
+ * This mimics LRU pool usage for new allocations and
+ * targets optimal filling when several pools contain
+ * blocks of the same size class.
+ */
+ size = pool->szidx;
+ next = usedpools[size + size];
+ prev = next->prevpool;
+ pool->nextpool = next;
+ pool->prevpool = prev;
+ next->prevpool = pool;
+ prev->nextpool = pool;
+ UNLOCK();
+ return;
+ }
+ /*
+ * Pool was not full
+ */
+ pool->freeblock = (block *)p;
+ if (--pool->ref.count != 0) {
+ UNLOCK();
+ return;
+ }
+ /*
+ * Pool is now empty, unlink from used pools
+ */
+ next = pool->nextpool;
+ prev = pool->prevpool;
+ next->prevpool = prev;
+ prev->nextpool = next;
+ /*
+ * Frontlink to free pools
+ * This ensures that previously freed pools will be allocated
+ * later (being not referenced, they are perhaps paged out).
+ */
+ pool->nextpool = freepools;
+ freepools = pool;
+ UNLOCK();
+ return;
+}
+
+/* realloc */
+
+void *
+_THIS_REALLOC(void *p, size_t nbytes)
+{
+ block *bp;
+ poolp pool;
+ uint size;
+
+#ifdef WITH_MALLOC_HOOKS
+ if (realloc_hook != NULL)
+ return (*realloc_hook)(p, nbytes);
+#endif
+
+ if (p == NULL)
+ return _THIS_MALLOC(nbytes);
+
+ /* realloc(p, 0) on big blocks is redirected. */
+ pool = (poolp )((block *)p - ((off_t )p & POOL_SIZE_MASK));
+ if (pool->pooladdr != pool || pool->magic != (uint )POOL_MAGIC) {
+ /* We haven't allocated this block */
+ if (!(nbytes > SMALL_REQUEST_THRESHOLD) && nbytes) {
+ /* small request */
+ size = nbytes;
+ goto malloc_copy_free;
+ }
+ bp = (block *)_SYSTEM_REALLOC(p, nbytes);
+ }
+ else {
+ /* We're in charge of this block */
+ size = (pool->szidx + 1) << ALIGNMENT_SHIFT; /* block size */
+ if (size >= nbytes) {
+ /* Don't bother if a smaller size was requested
+ except for realloc(p, 0) == free(p), ret NULL */
+ if (nbytes == 0) {
+ _THIS_FREE(p);
+ bp = NULL;
+ }
+ else
+ bp = (block *)p;
+ }
+ else {
+
+ malloc_copy_free:
+
+ bp = (block *)_THIS_MALLOC(nbytes);
+ if (bp != NULL) {
+ memcpy(bp, p, size);
+ _THIS_FREE(p);
+ }
+ }
+ }
+ return (void *)bp;
+}
+
+/* calloc */
+
+/* -- unused --
+void *
+_THIS_CALLOC(size_t nbel, size_t elsz)
+{
+ void *p;
+ size_t nbytes;
+
+#ifdef WITH_MALLOC_HOOKS
+ if (calloc_hook != NULL)
+ return (*calloc_hook)(nbel, elsz);
+#endif
+
+ nbytes = nbel * elsz;
+ p = _THIS_MALLOC(nbytes);
+ if (p != NULL)
+ memset(p, 0, nbytes);
+ return p;
+}
+*/
+
+/*==========================================================================*/
+
+/*
+ * Hooks
+ */
+
+#ifdef WITH_MALLOC_HOOKS
+
+void
+_SET_HOOKS( void *(*malloc_func)(size_t),
+ void *(*calloc_func)(size_t, size_t),
+ void *(*realloc_func)(void *, size_t),
+ void (*free_func)(void *) )
+{
+ LOCK();
+ malloc_hook = malloc_func;
+ calloc_hook = calloc_func;
+ realloc_hook = realloc_func;
+ free_hook = free_func;
+ UNLOCK();
+}
+
+void
+_FETCH_HOOKS( void *(**malloc_funcp)(size_t),
+ void *(**calloc_funcp)(size_t, size_t),
+ void *(**realloc_funcp)(void *, size_t),
+ void (**free_funcp)(void *) )
+{
+ LOCK();
+ *malloc_funcp = malloc_hook;
+ *calloc_funcp = calloc_hook;
+ *realloc_funcp = realloc_hook;
+ *free_funcp = free_hook;
+ UNLOCK();
+}
+#endif /* !WITH_MALLOC_HOOKS */